Psychology is defined as "the scientific study of behavior and mental processes". Philosophical interest in the human mind and behavior dates back to the ancient civilizations of Egypt, Persia, Greece, China, and India. Psychology as a field of experimental study began in 1854 in the German city of Leipzig, when Gustav Fechner created the first theory of how judgments about sensory experiences are made and how to experiment on them. Fechner's theory, recognized today as Signal Detection Theory, foreshadowed the development of statistical theories of comparative judgment and thousands of experiments based on his ideas (Link, S. W. Psychological Science, 1995). In 1879, Wilhelm Wundt founded the first psychological laboratory dedicated exclusively to psychological research in Leipzig, Germany. Wundt was also the first person to refer to himself as a psychologist. A notable precursor to Wundt was Ferdinand Ueberwasser (1752–1812), who designated himself Professor of Empirical Psychology and Logic in 1783 and gave lectures on empirical psychology at the Old University of Münster, Germany. Other important early contributors to the field include Hermann Ebbinghaus (a pioneer in the study of memory), William James (the American father of pragmatism), and Ivan Pavlov (who developed the procedures associated with classical conditioning). Soon after the development of experimental psychology, various kinds of applied psychology appeared. G. Stanley Hall brought scientific pedagogy to the United States from Germany in the early 1880s. John Dewey's educational theory of the 1890s was another example. Also in the 1890s, Hugo Münsterberg began writing about the application of psychology to industry, law, and other fields. Lightner Witmer established the first psychological clinic in the 1890s. James McKeen Cattell adapted Francis Galton's anthropometric methods to generate the first program of mental testing in the 1890s. In Vienna, meanwhile, Sigmund Freud independently developed an approach to the study of the mind called psychoanalysis, which became a highly influential theory in psychology. The 20th century saw a reaction to Edward Titchener's critique of Wundt's empiricism. This contributed to the formulation of behaviorism by John B. Watson, which was popularized by B. F. Skinner through operant conditioning. Behaviorism proposed emphasizing the study of overt behavior, because it could be quantified and easily measured. Early behaviorists considered the study of the mind too vague for productive scientific study. However, Skinner and his colleagues did study thinking as a form of covert behavior to which they could apply the same principles as overt behavior. The final decades of the 20th century saw the rise of cognitive science, an interdisciplinary approach to studying the human mind. Cognitive science again considers the mind as a subject for investigation, using the tools of cognitive psychology, linguistics, computer science, philosophy, behaviorism, and neurobiology. This form of investigation has proposed that a wide understanding of the human mind is possible, and that such an understanding may be applied to other research domains, such as artificial intelligence. There are conceptual divisions of psychology in "forces" or "waves", based on its schools and historical trends. This terminology was popularized among the psychologists to differentiate a growing humanism in therapeutic practice from the 1930s onwards, called the "third force", in response to the deterministic tendencies of Watson's behaviourism and Freud's psychoanalysis. Proponents of Humanistic psychology included Carl Rogers, Abraham Maslow, Gordon Allport, Erich Fromm, and Rollo May. Their humanistic concepts are also related to existential psychology, Viktor Frankl's logotherapy, positive psychology (which has Martin Seligman as one of the leading proponents), C. R. Cloninger's approach to well-being and character development, as well as to transpersonal psychology, incorporating such concepts as spirituality, self-transcendence, self-realization, self-actualization, and mindfulness. In cognitive behavioral psychotherapy, similar terms have also been incorporated, by which "first wave" is considered the initial behavioral therapy; a "second wave", Albert Ellis's cognitive therapy; and a "third wave", with the acceptance and commitment therapy, which emphasizes one's pursuit of values, methods of self-awareness, acceptance and psychological flexibility, instead of challenging negative thought schemes. A "fourth wave" would be the one that incorporates transpersonal concepts and positive flourishing, in a way criticized by some researchers for its heterogeneity and theoretical direction dependent on the therapist's view. A "fifth wave" has now been proposed by a group of researchers seeking to integrate earlier concepts into a unifying theory.
Early psychological thought
Many cultures throughout history have speculated on the nature of the mind, heart, soul, spirit, brain, etc. For instance, in Ancient Egypt, the Edwin Smith Papyrus contains an early description of the brain, and some speculations on its functions (described in a medical/surgical context) and the descriptions could be related to Imhotep who was the first Egyptian physician who anatomized and discovered the body of the human being. Though other medical documents of ancient times were full of incantations and applications meant to turn away disease-causing demons and other superstition, the Edwin Smith Papyrus gives remedies to almost 50 conditions and only two contain incantations to ward off evil. Ancient Greek philosophers, from Thales (fl. 550 BC) through even to the Roman period, developed an elaborate theory of what they termed the psuchẽ (psyche) (from which the first half of "psychology" is derived), as well as other "psychological" terms – nous, thumos, logistikon, etc. Classical Greece (fifth century BC), philosophers taught "naturalism", the belief that laws of nature shape our world, as opposed to gods and demons determining human fate. Alcmaeon, for example, believed the brain, not the heart, was the "organ of thought. "He tracked the ascending sensory nerves from the body to the brain, theorizing that mental activity originated in the region where the central nervous system is located and that the cause of mental illness resided within the brain. He applied this understanding to classify mental diseases and treatments. One of the most influential Ancient Greek influences on psychology came from the accounts of Plato (especially in the Republic), Pythagoras and of Aristotle (esp. Peri Psyches, also known by its Latin title, De Anima). Plato's tripartite theory of the soul, Chariot Allegory and concepts such as eros defined the subsequent Western Philosophy views of the psyche and anticipated modern psychological proposals. For example, concepts such as id, ego, super-ego and libido were interpreted by psychoanalysts as having been anticipated by Plato, to the extent that "in 1920, Freud decided to present Plato as the precursor of his own theory, as part of a strategy directed to define the scientific and cultural collocation of psychoanalysis". Other Hellenistic philosophers, namely the Stoics and Epicurians, diverged from the Classical Greek tradition in several important ways, especially in their concern with questions of the physiological basis of the mind. The Roman physician Galen addressed these issues most elaborately and influentially of all. The Greek tradition influenced some Christian and Islamic thought on the topic. In the Judeo-Christian tradition, the Manual of Discipline (from the Dead Sea Scrolls, c. 21 BC – 61 AD) notes the division of human nature into two temperaments or opposing spirits of either veracity or perversity. Walter M. Freeman proposes that Thomism is the philosophical system explaining cognition that is most compatible with neurodynamics, in a 2008 article in the journal Mind and Matter entitled "Nonlinear Brain Dynamics and Intention According to Aquinas". In Asia, China had a long history of administering tests of ability as part of its education system. Chinese texts from 2500 years ago mention neuropsychiatric illness, including descriptions of mania and psychosis with or without epilepsy. "Imbalance" was the mechanism of psychosis. Other conditions described include confusion, visual illusions, intoxication, stress, and even malingering. Psychological theories about stages of human development can be traced to the time of Confucius, about 2500 years ago. In the 6th century AD, Lin Xie carried out an early experiment, in which he asked people to draw a square with one hand and at the same time draw a circle with the other (ostensibly to test people's vulnerability to distraction). It has been cited that this was the first psychology experiment. India had a theory of "the self" in its Vedanta philosophical writings. Additionally, Indians thought about the individual's self as being enclosed by different levels known as koshas. Additionally, the Sankya philosophy said that the mind has five components, including manas (lower mind), ahankara (sense of I-ness), chitta (memory bank of mind), buddhi (intellect), and atman (self/soul). Patanjali was one of the founders of the yoga tradition, sometime between 200 and 400 BC (pre-dating Buddhist psychology) and a student of the Vedas. He developed the science of breath and mind and wrote his knowledge in the form of between 194 and 196 aphorisms called the Yoga Sutras of Patanjali. He developed modern Yoga for psychological resilience and balance. He is reputed to have used yoga therapeutically for anxiety, depression and mental disorders as common then as now. Buddhist philosophies have developed several psychological theories (see Buddhism and psychology), formulating interpretations of the mind and concepts such as aggregates (skandhas), emptiness (sunyata), non-self (anatta), mindfulness and Buddha-nature, which are addressed today by theorists of humanistic and transpersonal psychology. Several Buddhist lineages have developed notions analogous to those of modern Western psychology, such as the unconscious, personal development and character improvement, the latter being part of the Noble Eightfold Path and expressed, for example, in the Tathagatagarbha Sutra. Hinayana traditions, such as the Theravada, focus more on individual meditation, while Mahayana traditions also emphasize the attainment of a Buddha nature of wisdom (prajña) and compassion (karuṇā) in the realization of the boddhisattva ideal, but affirming it more metaphysically, in which charity and helping sentient beings is cosmically fundamental. Buddhist monk and scholar D. T. Suzuki describes the importance of the individual's inner enlightenment and the self-realization of the mind. Researcher David Germano, in his thesis on Longchenpa, also shows the importance of self-actualization in the dzogchen teaching lineage. Medieval Muslim physicians also developed practices to treat patients with a variety of "diseases of the mind". Ahmed ibn Sahl al-Balkhi (850–934) was among the first, in this tradition, to discuss disorders related to both the body and the mind. Al-Balkhi recognized that the body and the soul can be healthy or sick, or "balanced or imbalanced". He wrote that imbalance of the body can result in fever, headaches and other bodily illnesses, while imbalance of the soul can result in anger, anxiety, sadness and other nafs-related symptoms. Avicenna, similarly, did early work in the treatment of nafs-related illnesses, and developed a system for associating changes in the mind with inner feelings. Avicenna also described phenomena we now recognize as neuropsychiatric conditions, including hallucination, mania, nightmare, melancholia, dementia, epilepsy and tremor. Ancient and medieval thinkers who discussed issues related to psychology included:
Socrates of Athens (c. 470 – 399 BC). Emphasized virtue ethics. In epistemology, understood dialectic to be central to the pursuit of truth. As early as the 4th century BC, the Greek physician Hippocrates theorized that mental disorders had physical rather than supernatural causes. Plato's tripartite theory of the soul, Chariot Allegory and concepts such as eros defined the subsequent Western Philosophy views of the psyche and anticipated modern psychological proposals. Alcmaeon theorizes the brain in the seat of the mind. In 387 BC, Plato suggested that the brain is where mental processes take place. Boethius and his work represented an imaginary psychological dialogue between himself and philosophy, with philosophy personified as a woman, arguing that despite the apparent inequality of the world. In the 6th century AD, Lin Xie carried out an early psychological analysis experiment. It has been cited that this was the first psychology experiment. Ali ibn Sahl Rabban al-Tabari, who developed al-‘ilaj al-nafs (sometimes translated as "psychotherapy"), Padmasambhava was the 8th-century medicine Buddha of Tibet, called from the then Buddhist India to tame the Tibetans, and was instrumental in developing Tibetan psychiatric medicine. Patanjali founded Yoga and the method of psychological balance and resilience through breathing exercises and inner peace. Abu al-Qasim al-Zahrawi (Abulcasis), described head surgery. Ibn Tufail, who anticipated the tabula rasa argument and nature versus nurture debate. William of Ockham who has lot of interests in writing about logic and invented occams razor. Thomas Aquinas whose works allocated notion regarded emotions. Albertus magnus describes metaphysical morals in psychology and philosophical theories. Maimonides described rabies and belladonna intoxication. Witelo is considered a precursor of perception psychology. His Perspectiva contains much material in psychology, outlining views that are close to modern notions on the association of idea and on the subconscious.
Further development Many of the Ancients' writings would have been lost without the efforts of Muslim, Christian, and Jewish translators in the House of Wisdom, the House of Knowledge, and other such institutions in the Islamic Golden Age, whose glosses and commentaries were later translated into Latin in the 12th century. However, it is not clear how these sources first came to be used during the Renaissance, and their influence on what would later emerge as the discipline of psychology is a topic of scholarly debate.
Etymology and the early usage of the word The first print use of the term "psychology", that is, Greek-inspired neo-Latin psychologia, is dated to multiple works dated 1525. Etymology has long been attributed to the German scholastic philosopher Rudolf Göckel (1547–1628, often known under the Latin form Rodolphus Goclenius), who published the Psychologia hoc est: de hominis perfectione, animo et imprimis ortu hujus... in Marburg in 1590. Croatian humanist Marko Marulić (1450–1524) likely used the term in the title of a Latin treatise entitled Psichiologia de ratione animae humanae (c.1510–1517). Although the treatise itself has not been preserved, its title appears in a list of Marulic's works compiled by his younger contemporary, Franjo Bozicevic-Natalis in his "Vita Marci Maruli Spalatensis" (Krstić, 1964). The term did not come into popular usage until the German Rationalist philosopher, Christian Wolff (1679–1754) used it in his works Psychologia empirica (1732) and Psychologia rationalis (1734). This distinction between empirical and rational psychology was picked up in Denis Diderot's (1713–1780) and Jean le Rond d'Alembert's (1717–1783) Encyclopédie (1751–1784) and was popularized in France by Maine de Biran (1766–1824). In England, the term "psychology" overtook "mental philosophy" in the middle of the 19th century, especially in the work of William Hamilton (1788–1856).
Enlightenment psychological thought Early psychology was regarded as the study of the soul (in the Christian sense of the term). The modern philosophical form of psychology was heavily influenced by the works of René Descartes (1596–1650), and the debates that he generated, of which the most relevant were the objections to his Meditations on First Philosophy (1641), published with the text. Also important to the later development of psychology were his Passions of the Soul (1649) and Treatise on Man (completed in 1632 but, along with the rest of The World, withheld from publication after Descartes heard of the Catholic Church's condemnation of Galileo; it was eventually published posthumously, in 1664). Although not educated as a physician, Descartes did extensive anatomical studies of bulls' hearts and was considered important enough that William Harvey responded to him. Descartes was one of the first to endorse Harvey's model of the circulation of the blood, but disagreed with his metaphysical framework to explain it. Descartes dissected animals and human cadavers and as a result was familiar with the research on the flow of blood leading to the conclusion that the body is a complex device that is capable of moving without the soul, thus contradicting the "Doctrine of the Soul". The emergence of psychology as a medical discipline was given a major boost by Thomas Willis, not only in his reference to psychology (the "Doctrine of the Soul") in terms of brain function, but through his detailed 1672 anatomical work, and his treatise De anima brutorum quae hominis vitalis ac sentitiva est: exercitationes duae ("Two Discourses on the Souls of Brutes"—meaning "beasts"). However, Willis acknowledged the influence of Descartes's rival, Pierre Gassendi, as an inspiration for his work. The philosophers of the British Empiricist and Associationist schools had a profound impact on the later course of experimental psychology. John Locke's An Essay Concerning Human Understanding (1689), George Berkeley's Treatise Concerning the Principles of Human Knowledge (1710), and David Hume's A Treatise of Human Nature (1739–1740) were particularly influential, as were David Hartley's Observations on Man (1749) and John Stuart Mill's A System of Logic. (1843). Also notable was the work of some Continental Rationalist philosophers, especially Baruch Spinoza's (1632–1677) On the Improvement of the Understanding (1662) and Gottfried Wilhelm Leibniz's (1646–1716) New Essays on Human Understanding (completed 1705, published 1765). Another important contribution was Friedrich August Rauch's (1806–1841) book Psychology: Or, A View of the Human Soul; Including Anthropology (1840), the first English exposition of Hegelian philosophy for an American audience. German idealism pioneered the proposition of the unconscious, which Jung considered to have been described psychologically for the first time by physician and philosopher Carl Gustav Carus. Also notable was its use by Friedrich Wilhelm Joseph von Schelling (1775–1835), and by Eduard von Hartmann in Philosophy of the Unconscious (1869); psychologist Hans Eysenck writes in Decline and Fall of the Freudian Empire (1985) that Hartmann's version of the unconscious is very similar to Freud's. The Danish philosopher Søren Kierkegaard also influenced the humanistic, existential, and modern psychological schools with his works The Concept of Anxiety (1844) and The Sickness Unto Death (1849).
Transition to contemporary psychology Also influential on the emerging discipline of psychology were debates surrounding the efficacy of Mesmerism (a precursor to hypnosis) and the value of phrenology. The former was developed in the 1770s by Austrian physician Franz Mesmer (1734–1815) who claimed to use the power of gravity, and later of "animal magnetism", to cure various physical and mental ills. As Mesmer and his treatment became increasingly fashionable in both Vienna and Paris, it also began to come under the scrutiny of suspicious officials. In 1784, an investigation was commissioned in Paris by King Louis XVI which included American ambassador Benjamin Franklin, chemist Antoine Lavoisier and physician Joseph-Ignace Guillotin (later the popularizer of the guillotine). They concluded that Mesmer's method was useless. Abbé Faria, an Indo-Portuguese priest, revived public attention in animal magnetism. Unlike Mesmer, Faria claimed that the effect was 'generated from within the mind' by the power of expectancy and cooperation of the patient. Although disputed, the "magnetic" tradition continued among Mesmer's students and others, resurfacing in England in the 19th century in the work of the physician John Elliotson (1791–1868), and the surgeons James Esdaile (1808–1859), and James Braid (1795–1860) (who reconceptualized it as property of the subject's mind rather than a "power" of the Mesmerist's, and relabeled it "hypnotism"). Mesmerism also continued to have a strong social (if not medical) following in England through the 19th century (see Winter, 1998). Faria's approach was significantly extended by the clinical and theoretical work of Ambroise-Auguste Liébeault and Hippolyte Bernheim of the Nancy School. Faria's theoretical position, and the subsequent experiences of those in the Nancy School made significant contributions to the later autosuggestion techniques of Émile Coué. It was adopted for the treatment of hysteria by the director of Paris's Salpêtrière Hospital, Jean-Martin Charcot (1825–1893). Phrenology began as "organology", a theory of brain structure developed by the German physician, Franz Joseph Gall (1758–1828). Gall argued that the brain is divided into a large number of functional "organs", each responsible for particular human mental abilities and dispositions – hope, love, spirituality, greed, language, the abilities to detect the size, form, and color of objects, etc. He argued that the larger each of these organs are, the greater the power of the corresponding mental trait. Further, he argued that one could detect the sizes of the organs in a given individual by feeling the surface of that person's skull. Gall's ultra-localizationist position with respect to the brain was soon attacked, most notably by French anatomist Pierre Flourens (1794–1867), who conducted ablation studies (on chickens) which purported to demonstrate little or no cerebral localization of function. Although Gall had been a serious (if misguided) researcher, his theory was taken by his assistant, Johann Gaspar Spurzheim (1776–1832), and developed into the profitable, popular enterprise of phrenology, which soon spawned, especially in Britain, a thriving industry of independent practitioners. In the hands of Scottish religious leader George Combe (1788–1858) (whose book The Constitution of Man was one of the best-sellers of the century), phrenology became strongly associated with political reform movements and egalitarian principles (see, e.g., Shapin, 1975; but also see van Wyhe, 2004). Spurzheim soon spread phrenology to America as well, where itinerant practical phrenologists assessed the mental well-being of willing customers (see Sokal, 2001; Thompson 2021). The development of modern psychology was closely linked to psychiatry in the eighteenth and nineteenth centuries (see History of psychiatry), when the treatment of the mentally ill in hospices was revolutionized after Europeans first considered their pathological conditions. In fact, there was no distinction between the two areas in psychotherapeutic practice, in an era when there was still no drug treatment (of the so-called psychopharmacologicy revolution from 1950) for mental disorders, and its early theorists and pioneering clinical psychologists generally had medical background. The first to implement in the Western a humanitarian and scientific treatment of mental health, based on Enlightenment ideas, were the French alienists, who developed the empirical observation of psychopathology, describing the clinical conditions, their physiological relationships and classifying them. It was called the rationalist-empirical school, which most known exponents were Pinel, Esquirol, Falret, Morel and Magnan. In the late nineteenth century, the French current was gradually overcome by the German field of study. At first, the German school was influenced by romantic ideals and gave rise to a line of mental process speculators, based more on empathy than reason. They became known as Psychiker, mentalists or psychologists, with different currents being highlighted by Reil (creator of the word "psychiatry"), Heinroth (first to use the term "psychosomatic") Ideler and Carus. In the middle of the century, a "somatic reaction" (somatiker) formed against the speculative doctrines of mentalism, and it was based on neuroanatomy and neuropathology. In it, those who made important contributions to the psychopathological classification were Griesinger, Westphal, Krafft-Ebbing and Kahlbaum, which, in their turn, would influence Wernicke and Meynert. Kraepelin revolutionized as the first to define the diagnostic aspects of mental disorders in syndromes, and the work of psychological classification was followed to the contemporary field by contributions from Schneider, Kretschmer, Leonhard, and Jaspers. In Great Britain, there stand out in the nineteenth century Alexander Bain founder of the first journal of psychology, Mind, and writer of reference books on the subject at the time, such as Mental Science: The Compendium of Psychology, and the History of Philosophy (1868), and Henry Maudsley. In Switzerland, Bleuler coined the terms "depth psychology", "schizophrenia", "schizoid" and "autism". In the United States, the Swiss psychiatrist Adolf Meyer maintained that the patient should be regarded as an integrated "psychobiological" whole and emphasized psychosocial factors, lending support to early conceptions of "psychosomatic medicine", a precursor to behavioral medicine and other fields.
Emergence of German experimental psychology Until the middle of the 19th century, psychology was widely regarded as a branch of philosophy. Whether it could become an independent scientific discipline was questioned already earlier on: Immanuel Kant (1724–1804) declared in his Metaphysical Foundations of Natural Science (1786) that psychology might perhaps never become a "proper" natural science because its phenomena cannot be quantified, among other reasons. Kant proposed an alternative conception of an empirical investigation of human thought, feeling, desire, and action, and lectured on these topics for over twenty years (1772/73–1795/96). His Anthropology from a Pragmatic Point of View (1798), which resulted from these lectures, looks like an empirical psychology in many respects. Johann Friedrich Herbart (1776–1841) took issue with what he viewed as Kant's conclusion and attempted to develop a mathematical basis for a scientific psychology. Although he was unable to empirically realize the terms of his psychological theory, his efforts did lead scientists such as Ernst Heinrich Weber (1795–1878) and Gustav Theodor Fechner (1801–1887) to attempt to measure the mathematical relationships between the physical magnitudes of external stimuli and the psychological intensities of the resulting sensations. Fechner (1860) is the originator of the term psychophysics. Meanwhile, individual differences in reaction time had become a critical issue in the field of astronomy, under the name of the "personal equation". Early researches by Friedrich Wilhelm Bessel (1784–1846) in Königsberg and Adolf Hirsch led to the development of a highly precise chronoscope by Matthäus Hipp that, in turn, was based on a design by Charles Wheatstone for a device that measured the speed of artillery shells (Edgell & Symes, 1906). Other timing instruments were borrowed from physiology (e.g., Carl Ludwig's kymograph) and adapted for use by the Utrecht ophthalmologist Franciscus Donders (1818–1899) and his student Johan Jacob de Jaager in measuring the duration of simple mental decisions. The 19th century was also the period in which physiology, including neurophysiology, professionalized and saw some of its most significant discoveries. Among its leaders were Charles Bell (1774–1843) and François Magendie (1783–1855) who independently discovered the distinction between sensory and motor nerves in the spinal column, Johannes Müller (1801–1855) who proposed the doctrine of specific nerve energies, Emil du Bois-Reymond (1818–1896) who studied the electrical basis of muscle contraction, Pierre Paul Broca (1824–1880) and Carl Wernicke (1848–1905) who identified areas of the brain responsible for different aspects of language, as well as Gustav Fritsch (1837–1927), Eduard Hitzig (1839–1907), and David Ferrier (1843–1924) who localized sensory and motor areas of the brain. One of the principal founders of experimental physiology, Hermann Helmholtz (1821–1894), conducted studies of a wide range of topics that would later be of interest to psychologists – the speed of neural transmission, the natures of sound and color, and of our perceptions of them, etc. In the 1860s, while he held a position in Heidelberg, Helmholtz engaged as an assistant a young physician named Wilhelm Wundt. Wundt employed the equipment of the physiology laboratory – chronoscope, kymograph, and various peripheral devices – to address more complicated psychological questions than had, until then, been investigated experimentally. In particular he was interested in the nature of apperception – the point at which a perception occupies the central focus of conscious awareness. In 1864 Wundt took up a professorship in Zürich, where he published his landmark textbook, Grundzüge der physiologischen Psychologie (Principles of Physiological Psychology, 1874). Moving to a more prestigious professorship in Leipzig in 1875, Wundt founded a laboratory specifically dedicated to original research in experimental psychology in 1879, the first laboratory of its kind in the world. In 1883, he launched a journal in which to publish the results of his, and his students', research, Philosophische Studien (Philosophical Studies) (For more on Wundt, see, e.g., Bringmann & Tweney, 1980; Rieber & Robinson, 2001). Wundt attracted a large number of students not only from Germany, but also from abroad. Among his most influential American students were G. Stanley Hall (who had already obtained a PhD from Harvard under the supervision of William James), James McKeen Cattell (who was Wundt's first assistant), and Frank Angell (who founded laboratories at both Cornell and Stanford). The most influential British student was Edward Bradford Titchener (who later became professor at Cornell). Experimental psychology laboratories were soon also established at Berlin by Carl Stumpf (1848–1936) and at Göttingen by Georg Elias Müller (1850–1934). Another major German experimental psychologist of the era, though he did not direct his own research institute, was Hermann Ebbinghaus (1850–1909).
Psychoanalysis
Experimentation was not the only approach to psychology in the German-speaking world at this time. Starting in the 1890s, employing the case study technique, the Viennese physician Sigmund Freud developed and applied the methods of hypnosis, free association, and dream interpretation to reveal putatively unconscious beliefs and desires that he argued were the underlying causes of his patients' "hysteria". He dubbed this approach psychoanalysis. Freudian psychoanalysis is particularly notable for the emphasis it places on the course of an individual's sexual development in pathogenesis. Psychoanalytic concepts have had a strong and lasting influence on Western culture, particularly on the arts. Although its scientific contribution is still a matter of debate, both Freudian and Jungian psychology revealed the existence of compartmentalized thinking, in which some behavior and thoughts are hidden from consciousness – yet operative as part of the complete personality. Hidden agendas, a bad conscience, or a sense of guilt, are examples of the existence of mental processes in which the individual is not conscious, through choice or lack of understanding, of some aspects of their personality and subsequent behavior. Psychoanalysis examines mental processes which affect the ego. An understanding of these theoretically allows the individual greater choice and consciousness with a healing effect in neurosis and occasionally in psychosis, both of which Richard von Krafft-Ebing defined as "diseases of the personality". Freud founded the International Psychoanalytic Association in 1910, inspired also by Ferenczi. Main theoretical successors were Anna Freud (his daughter) and Melane Klein, particularly in child psychoanalysis, both inaugurating competing concepts; in addition to those who became dissidents and developed interpretations different from Freud's psychoanalytic one, thus called by some neo-freudians, or more correctly post-freudians: the most known are Alfred Adler (individual psychology), Carl Gustav Jung (analytical psychology), Otto Rank, Karen Horney, Erik Erikson and Erich Fromm. Jung was an associate of Freud's who later broke with him over Freud's emphasis on sexuality. Working with concepts of the unconscious first noted during the 1800s (by John Stuart Mill, Krafft-Ebing, Pierre Janet, Théodore Flournoy and others), Jung defined four mental functions which relate to and define the ego, the conscious self:
Sensation, which tell consciousness that something is there. Feelings, which consist of value judgments, and motivate our reaction to what we have sensed. Intellect, an analytic function that compares the sensed event to all known others and gives it a class and category, allowing us to understand a situation within a historical process, personal or public. And intuition, a mental function with access to deep behavioral patterns, being able to suggest unexpected solutions or predict unforeseen consequences, "as if seeing around corners" as Jung put it. Jung insisted on an empirical psychology on which theories must be based on facts and not on the psychologist's projections or expectations.
Early American Around 1875 the Harvard physiology instructor (as he then was), William James, opened a small experimental psychology demonstration laboratory for use with his courses. The laboratory was never used, at that time, for original research, and so controversy remains as to whether it is to be regarded as the "first" experimental psychology laboratory or not. In 1878, James gave a series of lectures at Johns Hopkins University entitled "The Senses and the Brain and their Relation to Thought" in which he argued, contra Thomas Henry Huxley, that consciousness is not epiphenomenal, but must have an evolutionary function, or it would not have been naturally selected in humans. The same year James was contracted by Henry Holt to write a textbook on the "new" experimental psychology. If he had written it quickly, it would have been the first English-language textbook on the topic. It was twelve years, however, before his two-volume The Principles of Psychology would be published. In the meantime textbooks were published by George Trumbull Ladd of Yale (1887) and James Mark Baldwin then of Lake Forest College (1889). William James was one of the founders of the American Society for Psychical Research in 1885, which studied psychic phenomena (parapsychology), before the creation of the American Psychological Association in 1892. James was also president of the British society that inspired the United States' one, the Society for Psychical Research, founded in 1882, which investigated psychology and the paranormal on topics such as mediumship, dissociation, telepathy and hypnosis, and it innovated research in psychology, by which, according to science historian Andreas Sommer, were "devised methodological innovations such as randomized study designs" and conducted "the first experiments investigating the psychology of eyewitness testimony (Hodgson and Davey, 1887), [and] empirical and conceptual studies illuminating mechanisms of dissociation and hypnotism"; Its members also initiated and organised the International Congresses of Physiological/Experimental psychology. In 1879 Charles Sanders Peirce was hired as a philosophy instructor at Johns Hopkins University. Although better known for his astronomical and philosophical work, Peirce also conducted what are perhaps the first American psychology experiments, on the subject of color vision, published in 1877 in the American Journal of Science (see Cadwallader, 1974). Peirce and his student Joseph Jastrow published "On Small Differences in Sensation" in the Memoirs of the National Academy of Sciences, in 1884. In 1882, Peirce was joined at Johns Hopkins by G. Stanley Hall, who opened the first American research laboratory devoted to experimental psychology in 1883. Peirce was forced out of his position by scandal and Hall was awarded the only professorship in philosophy at Johns Hopkins. In 1887 Hall founded the American Journal of Psychology, which published work primarily emanating from his own laboratory. In 1888 Hall left his Johns Hopkins professorship for the presidency of the newly founded Clark University, where he remained for the rest of his career. Soon, experimental psychology laboratories were opened at the University of Pennsylvania (in 1887, by James McKeen Cattell), Indiana University (1888, William Lowe Bryan), the University of Wisconsin (1888, Joseph Jastrow), Clark University (1889, Edmund Sanford), the McLean Asylum (1889, William Noyes), and the University of Nebraska (1889, Harry Kirke Wolfe). However, it was Princeton University's Eno Hall, built in 1924, that became the first university building in the United States to be devoted entirely to experimental psychology when it became the home of the university's Department of Psychology. In 1890, William James' The Principles of Psychology finally appeared, and rapidly became the most influential textbook in the history of American psychology. It laid many of the foundations for the sorts of questions that American psychologists would focus on for years to come. The book's chapters on consciousness, emotion, and habit were particularly agenda-setting. One of those who felt the impact of James' Principles was John Dewey, then professor of philosophy at the University of Michigan. With his junior colleagues, James Hayden Tufts (who founded the psychology laboratory at Michigan) and George Herbert Mead, and his student James Rowland Angell, this group began to reformulate psychology, focusing more strongly on the social environment and on the activity of mind and behavior than the psychophysics-inspired physiological psychology of Wundt and his followers had heretofore. Tufts left Michigan for another junior position at the newly founded University of Chicago in 1892. A year later, the senior philosopher at Chicago, Charles Strong, resigned, and Tufts recommended to Chicago president William Rainey Harper that Dewey be offered the position. After initial reluctance, Dewey was hired in 1894. Dewey soon filled out the department with his Michigan companions Mead and Angell. These four formed the core of The Chicago School of Psychology. In 1892, G. Stanley Hall invited 30-some psychologists and philosophers to a meeting at Clark with the purpose of founding a new American Psychological Association (APA). (On the history of the APA, see Evans, Staudt Sexton, & Cadwallader, 1992.) The first annual meeting of the APA was held later that year, hosted by George Stuart Fullerton at the University of Pennsylvania. Almost immediately tension arose between the experimentally and philosophically inclined members of the APA. Edward Bradford Titchener and Lightner Witmer launched an attempt to either establish a separate "Section" for philosophical presentati